Basically, a general memory device is constituted by a memory cell array and an operation voltage supply circuit. In the memory cell array, all the memory cells in the same row are electrically coupled to a respective write word line; and all the memory cells in the same column are electrically coupled to a respective bit line. The operation voltage supply circuit is configured to provide an operation voltage to all the memory cells in the same column in the memory cell array.
However, in the memory cell array, because all the memory cells in the same column are electrically coupled to one another, the bit line in the same column may have an increasing load while the memory cells in the same column are supplied with the operation voltage. Thus, an IR-Drop may occur, and consequently the memory cells may have a poor static noise margin (SNM) in the data writing period.